Digestion and Absorbtion 2 Flashcards Preview

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Flashcards in Digestion and Absorbtion 2 Deck (74):
1

What does maltose break down into and which enzyme is this reaction catalysed by

Glucose and glucose via maltase

2

What does sucrose isomaltase break down into and which enzyme is this reaction catalysed by

Glucose and fructose by sucrose isomaltase

3

Which two substances are converted to glucose in the liver

Fructose and galactose

4

What does catabolism of glucose produce

ATP

5

What is glycogenesis and where does this process occur

The conversion of glucose to glycogen and occurs in skeletal muscle and liver

6

What is glycogenolysis

The breakdown of glycogen to glucose

7

What is gluconeogenesis

When glucose is made from non-carbohydrate precursors such as fats and proteins

8

What are fully saturated glycogen stores

Where glucose is converted to free fatty acids and stored in adipocytes in the form on truglycerides

9

What are carbohydrates broken down by

Salivary and pancreatic amylase and brush border enzymes in the SI

10

What is glucose anabolism

Glucose storage and release, formation of glucose from proteins and fats, excess glucose stored as fat

11

Which cells rely almost entirely on glucose

CNS, retina and germinal epithelium cells

12

What are normal fasting blood glucose levels

3.5-7.5mmol-1

13

What is the predominant tissue in responding to reduced/ elevated blood glucose levels

The liver

14

What is persistently high blood glucose levels called

Hyperglycaemia

15

What is persistently low blood glucose levels called

Hypoglycaemia

16

What happens if blood glucose levels fall below 3mmol-1?

Loss of conciousness (coma)

17

What happens if blood glucose levels rise above 10mmol-1?

Glucose would appear in the urine, pH of blood would fall lead to coma

18

What happens if there are inadequate levels of glucose in the blood

Cells immediately shift to the catabolism of fats for energy

19

What happens if starvation occurs

Proteins are also used for energy after carbohydrate and fats are depleted

20

Which factors influence blood glucose levels

When eating takes place/ type of food eaten. The amount of physical and mental activity. The presence of hormones

21

Which two hormones are involved in the short term regulation of blood glucose levels

Insulin and glucagon

22

Which 4 hormones are involved in the long term regulation of blood glucose levels

Adrenaline, glucocorticoids, growth hormones, thyroid hormones.

23

What is the glycaemic index (GI) and what does it show

It is a rating system for foods containing carbohydrates and shows us how rapidly each food affects blood glucose levels (when that food is eaten on its own)

24

What are acniar cells and what do they secrete

They are in the pancreas and are part of the exocrine system so secrete digestive enzymes

25

What percentage of the pancreas is made up of Islet of Langerhans

2%

26

Which three types of cells is the Islet of Langerhans made up of

Alpha, beta and delta

27

How much of the islet of Langerhans consists of alpha cells

20%

28

What do alpha cells secrete

Glucagon

29

How much of the islet of Langerhans consists of beta cells

75%

30

What do beta cells secrete

Insulin

31

How much of the islet of Langerhans consists of delta cells

5%

32

What do delta cells secrete

Somatostatin

33

How long is insulin's half-life and what impact does this have on it's regulation of glucose

Insulin has a 5 minute half-life which means that it provides short term regulation

34

What type of protein is insulin

Globular

35

How many amino acids is insulin made from

51 amino acids

36

What does insulin respond to

High blood sugar levels

37

Which hormone responds to high blood sugar levels

Insulin

38

What impact does raised blood glucose levels have on cells in the Islets of Langerhans

Raised plasma glucose levels results in depolarisation of the beta cells

39

How long after a meal does plasma glucose reach max levels

Approximately 60 minutes after

40

Which elicits a greater response- oral glucose or intravenous glucose

Oral glucose

41

What do gastrointestinal hormones 'incretins' do

They enhance beta cell response to glucose

42

What are the 6 actions of insulin

1. Major targets= liver, adipose tissue and muscle mass
2. Increases glucose uptake by cells
3. Stimulates liver to convert glucose into glycogen (glyconeogenesis)
4. Inhibits gluconeogenesis
5. Stimulates excess glucose to be converted into fat (lipogensis)
6. Blood glucose levels drop

43

What is important to note about the CNS and insulin

Glucose uptake by the CNS is independent of insulin

44

Which is the most potent hyperglycaemic hormone

Glucagon

45

How many amino acids is glucagon made of

29 amino acids

46

What is the half life of glucagon

6 minutes

47

Describe the actions of glucagon in relation to insulin

The actions of glucagon directly oppose insulin

48

Why is glucagon secreted

In response to lowered plasma glucose to raise glucose levels

49

Which hormone inhibits glucagon secretion

Insulin

50

What are the nine actions of glucagon

1. If blood glucose falls to dangerous levels the alpha cells release glucagon
2. Glucagon exerts its effects on carbohydrate. fat and protein metabolism
3. The major target of glucagon is the liver
4. Glucagon converts glycogen into glucose (glycogenolysis)
5. It inhibits glycogen synthesis
6. It activates amino acid uptake and gluconeogenesis
7. It increases lipolysis
8. It provides a ready supply of metabolic substances
9. It enables glucose to be spared for the CNS

51

Changes in plasma glucose that occur during fasting then glucose rich meal

First 90 minutes= absorptive state of metabolism, insulin dormant
3-4 hours= post absorptive state of metabolism, glucagon dominant

52

Which hormones apart from insulin and glucagon are involves in the regulation of plasma glucose

Adrenal glucocorticoids, growth hormone, catecholamines, thyroid hormone

53

What functions do the hormones other than insulin and glucagon do

Maintain glycogen stores, stimulate gluconeogenesis, stimulate the metabolism of fatty acids and proteins. They play a significant role during prolonged fasting and conserve glucose for the CNS

54

What 2 metabolic effects does stomatostain have

1. Suppresses glucagon release from alpha cells
2. Suppresses release of insulin, pituitary tropic hormones, gastrin and secretin

55

What 2 metabolic effects does epinephrine (adrenaline) have

1. Enhances release of glucose from glycogen
2. Enhances release of fatty acids from adipose tissue

56

What 2 metabolic effects does cortisol have

1. Enhances gluconeogenesis
2. Antagonises insulin

57

What 2 metabolic effects does ACTH have

1. Enhances release of cortisol
2. Enhances release of fatty acids from adipose tissue inhibiting uptake by extrahepatic tissues

58

What metabolic effect does growth hormone have

Antagonises insulin, inhibiting uptake of extrahepatic tissues

59

What 2 metabolic effects does thyroxine have

1. Enhances release of glucose from glycogen
2. Enhances absorption of sugars from intestine

60

Which is the only hormone that lowers blood glucose levels

Insulin

61

What effect do all hormones (apart from insulin) have on blood glucose levels

They raise blood glucose levels

62

What is diabetes mellitus

A condition in which the body either does not produce enough, or does not properly respond to insulin or both

63

What are the 10 symptoms of diabetes mellitus

1. Always tired
2. Always hungry
3. Sexual problems
4. Sudden weight loss
5. Wounds that won't heal
6. Vaginal infections
7. Numb/ tingling hands or feet
8. Always thirsty
9. Frequent urination
10. Blurry vision

64

What are the other names for Type 1 diabetes

'Juvenile' diabetes/ insulin dependent diabetes mellitus (IDDM)

65

What are the other names for Type 2 diabetes

'Adult onset' diabetes, noninsulin dependent diabetes mellitus (NDDM)

66

Why is type 1 diabetes an organ specific immune disorder

It leads to the destruction of pancreatic beta cells resulting in the complete loss of insulin secretion

67

What 4 pros does exercise have in relation to diabetes risk

1. Decreased insulin resistance
2. Decreased risk of obesity and T2DM
3. Exercise may enhance insulin's binding to receptors on the muscle fibre
4. Thyfault and Booth 2011- increased sitting time leads to a reduction in insulin sensitivity

68

What is type 2 diabetes strongly linked to

Obesity

69

What is type 2 diabetes caused by

A reduction in pancreatic insulin or an increasing failure of tissues to respond to insulin

70

How can type 2 diabetes be controlled

Through diet

71

What is temporary glycaemia

Benign and asymptomatic

72

What does long term glyceamia lead to

Increased secretion of glucagon (insulin suppression), increase in glycogen breakdown, increase in rate of gluconeogenesis and increased lipolysis. Leads to further raising of blood glucose levels

73

What are the 3 consequences of hyperglycaemia

Polyuria, polydipsia, polyphagia

74

What is polyuria

Frequent and excessive urination. Osmotic pressure due to glucose in the urine